1. Field of the Invention
This invention relates to a color picture solid image-pickup element comprising: a solid image sensor including a photo-electric conversion section, a charge transfer section, and a transfer control section; and a matrix type microfilter having colored bits corresponding to picture elements and arranged on the photo-electric conversion section.
2. Background of the Invention
In general, the term "solid image sensor" and the term "solid image-pickup element" mean the same thing. However, for convenience in description, these terms will be defined as follows. The solid image sensor is used to detect only the brightness of a picture, i.e., it is used for monochromatic light. On the other hand, the solid image-pickup element is obtained by combining the solid image sensor with a microfilter, i.e., it is used for color pictures.
The above-described solid image-pickup element is well known in the art. The microfilter of the solid image-pickup element is in the form of a colored bit matrix. That is, the microfilter has colored bits of R (red), G(green), R, G, and so forth in first and second lines, fifth and sixth lines, and so forth in stated order, and has colored bits of G(green), B(blue), G, B, and so forth in third and fourth lines, seventh and eighth lines and so forth in the stated order. In the case of forming an interlacing type TV (television) picture field signal, the odd-numbered lines of the solid image-pickup element are successively read, and a 1H (one horizontal scanning period) delay line is used to obtain the signals of colors R, G and B from the picture.,signals of two lines. In this case, the luminance signal Y is formed by weighted-addition, and the color difference signals R-Y and B-Y can be formed in the same manner.
The above-described system is excellent. Although the color solid image-pickup element has substantially the same number of picture element as the monochromatic solid image sensor, the decrease in resolving power of the solid image-pickup element is minimized as it is designed for color pictures.
Owing to the recent improvement of the LSI manufacturing technique, more picture elements can be formed in one and the same chip. Therefore, if the number of picture elements are increased both in a horizontal direction and in a vertical direction and the above-described system is employed, then a color picture solid image-pickup element considerably high in resolving power can be obtained. It is apparent from a simple calculation that the color picture resolving power substantially equal to that of the monochromatic light solid image sensor can be obtained by increasing the number of picture elements by a factor of three (3). However, in a system in which, as in the case of TV pictures, the number of scanning lines is predetermined, it is difficult to increase the number of picture elements by three times.
Therefore, a variety of methods have been proposed in the art in which the number of picture elements is doubled both in a horizontal direction and in a vertical direction to obtain a resolving power equivalent to that of the monochromatic light solid image sensor.
One example of a solid image-pickup element in which the number of picture elements in a vertical direction is doubled according to the above-described system is known in the art. However, the solid image-pickup element is disadvantageous in that, since different colors are alternately arranged in each horizontal line of picture elements, the effective sampling frequency is decreased to half, and therefore the horizontal resolving power is insufficient.